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(No Model.) 2 SheetsSheet 1.

A. J. STEVENS.

VALVE GEAR POE STEAM ENGINES. No. 324,964. Patented Aug. 25, 1885.

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2 S N E V E T S u A VALVE GEAR FOR STEAM ENGINES.

Patented Aug. 25, 1885.

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UNrrEn STATES PATENT QEFICE.

ANDRE J. STEVENS, OF SACRAMENTO, CALIFORNIA.

VALVE-GEAR FOR STEAM-ENGINES.

-EPEQIFICATION forming part of Letters Patent No. 324,964, dated August 25, 1885.

Application filed July 29, 1584.

To all whom it may concern.-

Be it known that 1, ANDREW J. STEVENS, a citizen of the United States, residing in the city of Sacramento, county of Sacramento, and State of California, have invented certain new and useful Improvements in ValveGear for Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the said invention, and of the manner in which I proceed to construct, produce, apply, and use it, reference being had to the drawings accompanying and forming a part of this specification.

My invention relates to an improved valvegear or valve actuating mechanism having certain features of adjustment and action that give a variable cut-off and expansion valve-gear for steam-engines; and it is designed more particularly for use and combination with the improvement heretofore invented by me and described in Letters Patent of the United States No. 288,133, issued to me on the 6th November, 1883.

That invention, having for its essential features the connection of the valves by independent valve-rods, with a rotary disk receiving a movement of rotation upon a center from the engine-piston, and also a general oscillation or travel in a curvilinear path from a valve mechanism of the ordinary kind, produces an independent movement of one valve over the other, and a certain variable motion that qualifies the general travel; but this construction, (which I shall hereinafter always refer to as my former patent,) while capable of considerable variation in its degree of action, had no adjustability to produce certain qualities of expansion and cut-off in the valvemotion; and to such end and purpose, therefore, my present invention is produced and applied.

It consists in the construction and combination of parts, as herein more particularly described, in and by which there is obtained a valve-gear of great simplicity with delicacy of action under adjustment.

Referring to the drawings, Figure 1 represents the gear and its connection with the valve-rods and the engine cross-head, the engine being at midstroke and the mechanism set at midgear. Fig. 2 is a plan or top (No model.)

view. Figs. 3 and 4 illustrate the position of the parts when the piston is at the end of its stroke, the first position being the forward and the other the back stroke.

A B are the valverods, O the engine-piston, and D the cross'head. E, the lever-arm, has its lower end connected by a link, 9, to the cross'head, and is fixed to the end of the oscillating rod F by a pivot on which it is capable of rotating. These parts, and the connection of the valve-rods to the head of the governorlever E, at the points it h on opposite sides of the center of rota-tion, are contained in my former patent; but the parts in this improvement by which the eccentric is connected with this lever or part E having the valve-rods attached to it, are of such construction and op eration that from the general movements of the eccentric a variation in the throw of the valves is obtained, and by adj ustmcnt is varied in degree as required. This mechanism, in connection and joint operation with the differential movement obtained from the independent valve-rods and oscillatory lever E, produces a valve-gear of peculiar character of motion.

The rocker-shaft I has two arms, J J fixed substantially at right angles, so that the cocentric-rod K, being attached to the end of the one J, gives vertical movement of the other, J, from which the point in" receives motion in substantially a rectilinear path, or back and forth from the point of oscillation above. This end J of the bell-crank is connected by the link It to the center at of the toggle N P, and the two arms or members of this jointed link N P are attached at one end to the tumble-shaft L, at m, and at the other end to the point m which is the center of rotation of the head of the lever E.

The tumbler-shaft L has two arms, L U, to one of which the reach-rod M from the reversing-lever is attached, at M and to the other, connection of the end N of the toggle is made at m. This point an is a fixed one during the general movement of the valve-gear, but is set up and down by the adjustment of the arm L about the center L, which change of position shifts the center at either above or below the line of the center I of the bell-crank, accord ing as the tumble-shaft arm is turned up or down. The link R connects the point m and the arm J together, and the two are of equal length. Movement of the arm in a vertical path, therefore, throws the point m longitudinally, and substantially in a rectilinear path, back and forth. The degree of this motion thus imparted to the point m is also regulated by the position of the center m with respect to the fixed center I, upon which the bellcrank moves. When set above this center I at any point, the extension and contraction of the toggle N P gives the forward motion, while the action of the valves is reversed by dropping the center on below the shaft I, and ac cording as the difference between these two centers m I is increased so is the angular position of the arm of the bell-crank and its link R varied. Of these parts, therefore, the link N is a lifting-link to set the center on up and down. The link P is a drivinglink, and the connection R is, by virtue of its position and action, an expansion and reversing link.

Having thus fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. The combination,with thebell-crank J J adapted to receive motion from an eccentric or other driving mechanism, of the links R I, one connected either directly or indirectly to the valve-rods and the other to the bell-crank, and at their inner ends connected to a common pivot or center, m, which is confined to a movement in the arc of avcircle and is also adjustable up and down, substantially in the manner set forth.

2. In a valve-gear, the combination, with the eccentric-rod K, of the bell-crank connection, by which horizontal movement of the eccentric is changed into vertical motion, and the driving-link P and link It connecting the bell-crank and driving-link together, said links, at their common "pivot m being connected to the arm L of a tumble-shaft, L, by link N, substantially as and for operation as set forth.

3. The combination, with the oscillating disk or head of the lever E, having oscillating movement from as well as rotation on the end of the suspension-link F, and a connection of the valverods A B thereto as well as a con nection of the end of the lever to the piston, of the rocker-shaft I, arms J J*, links 1? R, tumble-shaft L, and lifting-link N, substantially as described.

ANDREW? J. STEVENS. [Ls] Witnesses:

ALBERTIS ANDREW VVORTHINGTON, FRANK LENOIR. 

